STEREOLOGICAL CORRECTION OF LINEAR GRADE DISTRIBUTIONS FOR MINERAL LIBERATION

Accurate measurement of the distribution of particle composition by im age analysis requires a reliable method for the calculation of the ste reological correction that must be applied to the composition distribu tion that is measured using linear and areal section measurements. Lin ear or areal measurements are usually obtained from SEM images of poli shed sections through a representative sample of the particle populati on. A stereological correction based on the solution f(v) of the inver se problem Kf(v) = F-l is developed in this paper. The kernel matrix w as accurately measured using a sample of dolomite-sphalerite ore which was carefully fractionated using a batch magnetic-fluid separation te chnique. The solution of the inverse problem is obtained based on the minimization of \\kf(v) - F-l\\ + lambda Sigma(f)f(v)(f) Inf(v)(j) sub ject to the constraints f(v)(j) greater than or equal to 0 and Sigma(j )f(v)(j) = 1. A method is presented for selecting the most appropriate kernel to suit the mineralogical texture of the ore. The stereologica l correction is shown to be accurate by comparison against real labora tory data measured using magnetic-fluid fractionation techniques. The method is convenient and is suitable for routine use in image analysis systems. (C) 1998 Elsevier Science S.A. All rights reserved.